Thank you, Michael. Since many of us were occupied with other matters overthe Fourth of July holiday, if it hadn't been for your prompt response theremight not have been anyone to encourage undergraduates and high schoolstudents to continue sending us their homework problems, and our reputationfor undermining the efforts of classroom teachers might have suffered.

>>> On 3 Jul 2000, R. wrote:>>> Find:>> lim (t+1)^9 * (t^2-1)>> x --> -2>> Would you just substitute in the -2 for the t's and figure it out>> algebraically?>>>> Sure, you don't need limits to figure this one out, limits> should be used when you can't just plug in the numbers, for example,> sinx/x for x-->0 or (1+x)^x for x-->0. There are some artificially cooked> situations when you plug in and get the wrong number, for example,> f(x)=1 for x=/=0, f(0)=0, then lim (x-->0) f(x) = 1, while f(0)=0.> But if you deal with expressions involving the elementary functions,> you can plug in and get the limit. It's because the elementary functions> are continuous.>> --Michael>>>> ------------------------------------------------------------>> -HOW TO UNSUBSCRIBE>> To UNSUBSCRIBE from the calc-reform mailing list,> send mail to:>> majordomo@ams.org>> with the following in the message body:>> unsubscribe calc-reform your_email_address>>> -Information on the subject line is disregarded.>